1. Field of the Disclosure
Generally, the present disclosure relates to the field of integrated circuits and semiconductor devices and, more particularly, to an ion implant device comprising an orienter pedestal for orienting a wafer before it is transferred for implantation processing to a process platen of the ion implant device.
2. Description of the Related Art
The fabrication of advanced integrated circuits, such as CPUs, storage devices, application specific integrated circuits (ASICs) and the like, requires the formation of a large number of circuit elements on a given chip area according to a specified circuit layout. In a wide variety of electronic circuits, field effect transistors represent one important type of circuit element that substantially determines performance of the integrated circuits. Generally, a plurality of process technologies are currently practiced for forming field effect transistors (FETs), wherein, for many types of complex circuitry, MOS technology is currently one of the most promising approaches due to the superior characteristics in view of operating speed and/or power consumption and/or cost efficiency. During the fabrication of complex integrated circuits using, for instance, CMOS technology, millions of N-channel transistors and P-channel transistors are formed on a substrate including a crystalline semiconductor layer.
Generally, a set of processing steps is performed on a lot of wafers using a variety of process tools, including photolithography steppers, etch tools, deposition tools, polishing tools, rapid thermal process tools, implantation tools, etc. The technologies underlying semiconductor process tools have attracted increased attention over the last several years, resulting in substantial refinements. However, despite the advances made in this area, many of the process tools that are currently commercially available suffer certain deficiencies. In particular, such tools often lack advanced process data monitoring capabilities, such as the ability to provide historical parametric data in a user-friendly format, as well as event logging, real-time graphical display of both current processing parameters and the processing parameters of the entire run, and remote, i.e., local site and worldwide, monitoring. These deficiencies can result in non-optimal control of critical processing parameters, such as throughput, accuracy, stability and repeatability, processing temperatures, mechanical tool parameters, and the like. This variability manifests itself as within-run disparities, run-to-run disparities and tool-to-tool disparities that can propagate into deviations in product quality and performance, whereas an ideal monitoring and diagnostics system for such tools would provide a means of monitoring this variability, as well as providing means for optimizing control of critical parameters.
Ion implantation is a very complex and widely used process in the manufacture of integrated circuit devices. Ion implantation is a technique used to implant a dopant material, e.g., arsenic or boron, into a structure, e.g., a substrate, to form very precise implant regions having a certain dopant concentration and profile. Ion implantation processes may also be performed to implant dopant materials into a layer of material. Very precise control of ion implantation processes is desirable because of the impact the implant regions may have on the performance capabilities of the ultimate integrated circuit product. For example, precise control of the ion implantation processes performed to form the source/drain regions for a transistor or to control the threshold voltage of the transistor is required if the ultimate devices are to operate as intended. Typically, in modern semiconductor manufacturing facilities, ion implantation processes are performed on a group or batch of substrates, e.g., wafers. The number of substrates processed in each batch may vary depending on the ion implant equipment used to perform the process. Most of the batch-type ion implant equipment may perform the ion implant process on 13 or 17 wafers at a time. There is great interest in attempting to insure that the processes performed in such ion implant tools are performed correctly. Moreover, in some cases, if the ion implant processes are performed incorrectly, the substrates subjected to such incorrect processes must be destroyed. That is, it is very difficult, if not impossible, to rework substrates subjected to erroneous ion implant processes.
Ion implantation processes are very complex, and the successful performance of such ion implantation processes depends on a number of related parameters of the process, e.g., implant dose, implant energy level, gas flow rates, the current and voltage levels of the filament, ion beam current, number of scans, etc. To achieve a desired to targeted result, modern ion implant equipment may automatically adjust or tune the ion beam prior to performing an implant process in an effort to insure that the implant process performed by the tool will produce acceptable results. That is, the ion implant tool attempts to tune or adjust a plurality of these related parameters such that a selected combination of these parameters will produce the intended results. The tuning process is a relatively time-consuming process.
In an implantation device, accurate wafer orientation before wafer transfer to a process platen by means of an orienter pedestal is mandatory. In particular, the accurate orienter lift up/down alignment of an implanter is difficult and time-consuming. The alignment of the orienter lift up and down positions ensures that the wafer is smoothly transferred to and from the orienter wafer lift chuck without slippage or damage. An exactly adjusted height of the orienter pedestal is mandatory for successful wafer orientation. The alignment is conventionally based on an orient up gauge and an orient down gauge. Since original calibration gauges provided by suppliers are usually not accurate enough to guarantee a satisfying alignment, the accurate orienter lift up/down alignment poses severe problems when using an implantation device.
With respect to conventional orienter lift up/down alignment it is referred, for example, to a manual by Varian Semiconductor Equipment, Orienter Lift Up/Down, Alignment, E82295700, Revision A, 10/2011 (Alignment procedure for Universal End Station X, Orienter E11320430); see also EP0246117A2. The cumbersome conventional alignment procedure comprises the steps of raising an orienter to an up position, rotating robot arms to the orienter, checking the orienter lift up position, adjusting the orienter pedestal height, lowering orienter to down position, checking the orienter lift down position and initializing a robot arm followed by robot to orienteralignment (see above-mentioned manual by Varian Semiconductor Equipment). The step of checking the orienter lift up position comprises placing the up gauge onto the wafer lift chuck so that an alignment pin of the gauge is inserted into a hole in the center of the wafer lift chuck and rotating the gauge so that an open slot is oriented towards a higher robot end-effector followed by using a robot arm to manually move a higher end-effector towards the wafer lift chuck and verifying that the end-effector fits into the open slot of the gauge and just touches the bottom of the slot. Adjusting the orienter pedestal height comprises loosening a split clamp screw and two additional screws and, after the adjustment, usually, the step of checking the orienter lift up position has to be repeated, etc. The step of lowering the orienter to the down position comprises placing the down gauge onto the wafer lift chuck so that an alignment pin of the gauge is inserted into a hole in the center of the wafer lift chuck and rotating the gauge so that an open slot is oriented towards a higher robot end-effector followed by using a robot arm to manually move a higher end-effector towards the wafer lift chuck and verifying that the end-effector fits into the open slot of the gauge and just touches the bottom of the slot.
In view of the above, there is a need for a tool for orienter pedestal alignment (orienter pedestal lift up/down alignment) of an ion implanter that is easy to use with a high reproducibility.